2008 cobalt question - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

joe h · 01-14-2011, 06:03 PM

Bought an used 2008 cobalt sport with a 4 speed automatic, driving 75mph on the interstate the car is turning 2800rpms. Service departments I have talked to will give me figures ranging as low as 1900 to as high as 2600. So today I bring it to the dealership and of course the technician says nothing is wrong, could not find any codes. If this true, and the car is running right, this would be the highest any automatic, that I have owned, has turned since a 94 suburu with a 3 speed. and 200rpms higher than any 4 speed I have ever owned.

Just wondering if anyone has had any experience with this car, or similar car, that can confirm this car is running properly or not.

Rwarchol · 01-14-2011, 06:35 PM

My old Sunfire ran around 3k when at 70mph so that seems about right.

Entaille · 01-14-2011, 06:53 PM

maybe the gears were changed out?

a_Username · 01-14-2011, 07:36 PM

Sounds about right.

*Mr. Wyndham* · 01-14-2011, 09:07 PM

In line with what my 2008 LS is doing. I rarely go above 65 because of it...exponential fuel-economy reductions hurt....

joe h · 01-14-2011, 11:04 PM

Just seems strange that over the last 20 years gm has been gearing their overdrive lower, but this one car line they decided to go with nearly 3000 rpm. I have a 2008 impala that runs at 1900 at 75, even my old 96 cavalier with a 4 speed was around 2600.

*Mr. Wyndham* · 01-14-2011, 11:08 PM

Quote:

Originally Posted by joe h

Just seems strange that over the last 20 years gm has been gearing their overdrive lower, but this one car line they decided to go with nearly 3000 rpm. I have a 2008 impala that runs at 1900 at 75, even my old 96 cavalier with a 4 speed was around 2600.

It all depends on the engine output/weight of the vehicle, etc...The Camaro is hardly above idle at 55, and not much more than 1600 at 75, I think. But then, it also has a 6-speed with a deep overdrive in 6th...

*DGthe3* · 01-15-2011, 12:01 AM

a little under 3000 rpm for a GM 4banger with a 4 speed hydramatic sounds about right

*DGthe3* · 01-15-2011, 12:05 AM

Quote:

Originally Posted by joe h

Just seems strange that over the last 20 years gm has been gearing their overdrive lower, but this one car line they decided to go with nearly 3000 rpm. I have a 2008 impala that runs at 1900 at 75, even my old 96 cavalier with a 4 speed was around 2600.

It should be the exact same as your Cavalier. Same transmission ratios, same overdrive. Only difference would be the OD of the wheels & tires.

Number 3 · 01-15-2011, 08:03 AM

Try this. The inputs are readily available if not in the owers manual.

http://www.csgnetwork.com/multirpmcalc.html

Reborn · 01-15-2011, 09:28 PM

Yeah, that sounds right. My 2008 Cobalt Sport does the same about the same at that speed.

joe h · 01-15-2011, 10:07 PM

Good to know, buying the car used I had some jitters, so anything slightly different had me concerned at first, but everything seems fine. Also didn't realize until a couple days ago it was suppose to take 91 octane, I was using 89 and that was most likely contributing to the lower than advertised gas mileage.

a_Username · 01-15-2011, 11:04 PM

Quote:

Originally Posted by joe h

Good to know, buying the car used I had some jitters, so anything slightly different had me concerned at first, but everything seems fine. Also didn't realize until a couple days ago it was suppose to take 91 octane, I was using 89 and that was most likely contributing to the lower than advertised gas mileage.

wut? I didn't know that either.

joe h · 01-15-2011, 11:24 PM

yep, it is buried in the manual. Also wikipedia lists the compression ratio as 10.4:1. But the car doesn't seem as finicky as the camaro.

01-14-2011, 06:03 PM	#1
joe h Drives: victory red 2010 camaro 2ss/rs Join Date: Mar 2010 Location: bismarck, nd Posts: 125	2008 cobalt question Bought an used 2008 cobalt sport with a 4 speed automatic, driving 75mph on the interstate the car is turning 2800rpms. Service departments I have talked to will give me figures ranging as low as 1900 to as high as 2600. So today I bring it to the dealership and of course the technician says nothing is wrong, could not find any codes. If this true, and the car is running right, this would be the highest any automatic, that I have owned, has turned since a 94 suburu with a 3 speed. and 200rpms higher than any 4 speed I have ever owned. Just wondering if anyone has had any experience with this car, or similar car, that can confirm this car is running properly or not.

01-14-2011, 06:53 PM	#3
Entaille Drives: 2018 Camaro 2SS Join Date: Aug 2010 Location: Lake Stevens Posts: 1,005	maybe the gears were changed out? __________________

01-14-2011, 09:07 PM	#5
Mr. Wyndham I used to be Dragoneye... Drives: 2018 ZL1 1LE Join Date: Jan 2007 Location: Buffalo, NY Posts: 31,876 View My Garage	In line with what my 2008 LS is doing. I rarely go above 65 because of it...exponential fuel-economy reductions hurt.... __________________ *"Keep the faith."* - Fbodfather

01-15-2011, 12:01 AM	#8
DGthe3 Moderator.ca Drives: 05 Grand Am GT Join Date: Jul 2007 Location: Niagara, Canada Posts: 25,372	a little under 3000 rpm for a GM 4banger with a 4 speed hydramatic sounds about right __________________ Note, if I've gotten any facts wrong in the above, just ignore any points I made with them __________________ Originally Posted by FbodFather My sister's dentist's brother's cousin's housekeeper's dog-breeder's nephew sells coffee filters to the company that provides coffee to General Motors...... ........and HE WOULD KNOW!!!! __________________ Camaro Fest sub-forum

01-15-2011, 08:03 AM	#10
Number 3 Hail to the King baby! Drives: '19 XT4 2.0T & '22 VW Atlas 2.0T Join Date: Dec 2008 Location: Illinois Posts: 12,172 View My Garage	Try this. The inputs are readily available if not in the owers manual. http://www.csgnetwork.com/multirpmcalc.html __________________ "Speed, it seems to me, provides the one genuinely modern pleasure." - Aldous Huxley

01-14-2011, 06:35 PM	#2
Rwarchol Drives: 2010 1LT SIM A6, 2005 GTO TR A4 Join Date: Jul 2009 Location: Buffalo, NY Posts: 342	My old Sunfire ran around 3k when at 70mph so that seems about right.

01-14-2011, 07:36 PM	#4
a_Username Drives: 2010 2SS Camaro Join Date: Jul 2009 Location: Murfreesboro, TN Posts: 3,890 View My Garage	Sounds about right.

01-14-2011, 11:04 PM	#6
joe h Drives: victory red 2010 camaro 2ss/rs Join Date: Mar 2010 Location: bismarck, nd Posts: 125	Just seems strange that over the last 20 years gm has been gearing their overdrive lower, but this one car line they decided to go with nearly 3000 rpm. I have a 2008 impala that runs at 1900 at 75, even my old 96 cavalier with a 4 speed was around 2600.

01-15-2011, 09:28 PM	#11
Reborn Drives: 2008 Chevrolet Cobalt Join Date: Jul 2008 Location: Minneapolis Posts: 112	Yeah, that sounds right. My 2008 Cobalt Sport does the same about the same at that speed. __________________

01-15-2011, 10:07 PM	#12
joe h Drives: victory red 2010 camaro 2ss/rs Join Date: Mar 2010 Location: bismarck, nd Posts: 125	Good to know, buying the car used I had some jitters, so anything slightly different had me concerned at first, but everything seems fine. Also didn't realize until a couple days ago it was suppose to take 91 octane, I was using 89 and that was most likely contributing to the lower than advertised gas mileage.

01-15-2011, 11:24 PM	#14
joe h Drives: victory red 2010 camaro 2ss/rs Join Date: Mar 2010 Location: bismarck, nd Posts: 125	yep, it is buried in the manual. Also wikipedia lists the compression ratio as 10.4:1. But the car doesn't seem as finicky as the camaro.